An IQ test for adults is one normed on adult samples, like the WAIS-5 or the adult-only RIOT IQ test. See which tests qualify and where to take one.
Dr. Russell T. WarneChief Scientist
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An IQ test for adults is a test whose questions and, more importantly, whose norms were built on adult samples. Your performance is compared with a reference group of other adults, and the result lands on a scale with an average of 100 and a standard deviation of 15. Only a short list of tests genuinely meets that standard: the Wechsler Adult Intelligence Scale (WAIS-5) given by psychologists, the Stanford-Binet 5, Raven's Advanced Progressive Matrices, Mensa's admission testing, and, online, the RIOT IQ test (the Reasoning and Intelligence Online Test), which is normed exclusively on adults 18 and older. This article explains what adult norming means, which tests qualify, and where you can actually take one.
What makes an IQ test an adult test
The heart of the matter is the "norm group," the reference sample a test uses to convert raw performance into an IQ. Modern tests report a "deviation IQ": a number that describes where you stand within your own age group's distribution, with a mean of 100 and a standard deviation of 15. Roughly two-thirds of people score between 85 and 115, and about 2 percent score above 130.
The original childhood formula (mental age divided by chronological age, times 100) is obsolete for exactly this reason. "Mental age" stops rising in adulthood, so a ratio built on it becomes meaningless for a 40-year-old. Adult tests solved the problem with separate norms for each adult age band. The WAIS-5's norms run from age 16 through 90 years 11 months, so a 72-year-old is compared with peers of the same age rather than with college students. A quiz with no adult norm group, however slick, has no adult yardstick to measure you against.
Tests genuinely designed and normed for adults
Four instruments dominate serious adult testing, and each documents its adult norms publicly.
• The WAIS-5: Pearson's Wechsler Adult Intelligence Scale, published in its fifth edition in 2024, is the clinical standard. Pearson describes the WAIS as the most widely used measure of intelligence in adults and older adolescents ages 16 through 90:11. The seven-subtest full-scale IQ takes about 45 minutes and the ten primary subtests about 60, spanning verbal comprehension, visual spatial, fluid reasoning, working memory, and processing speed. Our guide to the WAIS IQ test covers it in depth.
• The Stanford-Binet 5: The SB5 assesses examinees from age 2 to 85 and beyond, measures five factors, and reports full-scale IQ reliabilities of .95 to .98, with typical administration around 5 minutes per subtest. It is an all-ages instrument rather than an adult-specific one, but its adult norms are real and it remains a clinical mainstay.
• Raven's Advanced Progressive Matrices: A nonverbal matrices test normed for ages 17 and older (plus a younger band), untimed at roughly 40 to 60 minutes. Because every item uses the same matrix format, it is best read as an estimate of abstract, fluid reasoning rather than a full IQ profile.
• The RIOT IQ test: Developed by intelligence researcher Dr. Russell T. Warne and built on the Cattell-Horn-Carroll model, the RIOT IQ test is explicitly an IQ test for adults (18+), with 15 subtests across six cognitive indices. Every version is normed on US-born, native English speakers aged 18 and older.
Where adults can take a credible IQ test
• A licensed psychologist: The WAIS-5 and SB5 are C-level qualification instruments, meaning the public cannot buy or self-administer them. A clinician gives the test one-on-one and interprets the results, which is the route to take when the score has legal, clinical, or educational consequences.
• Mensa admissions testing: American Mensa tests candidates aged 14 and older. A session costs $60 through a local group or $99 for private testing, takes between one and two hours, and requires photo ID. Note the output: Mensa reports whether you scored at or above the 98th percentile, an admissions screen rather than a full IQ profile. Our article on how to join Mensa walks through the process.
• Credible online testing: The RIOT IQ test is the online option built for and normed only on adults. The free version takes about 8 minutes and reports a margin of error of 14.9 IQ points in either direction; the Basic version takes about 13 minutes and narrows that to 5.6 points; the Full version takes about 52 minutes, covers all 15 subtests, and narrows it to 3.7. You can start with the free version and upgrade to a longer version if the estimate makes you curious.
Age does not put a real score out of reach
A common worry is that adult IQ cannot be measured because adults stopped developing years ago. Deviation scoring answers it: you are ranked against your own age group, so there is nothing to outgrow.
The scores themselves are also surprisingly durable. In the Lothian Birth Cohort study, researchers retested the same people on the same test at ages 11 and 90, and the correlation between the two sittings was .54, rising to .67 after correcting for range restriction. Rank order holds up across nearly the whole lifespan, even as specific abilities shift.
Those shifts are real, which is why age-band norms matter. A study of 48,537 online participants found that some abilities peak around high school graduation, others plateau in early adulthood, and still others do not peak until the 40s or later. Processing speed in particular declines steadily across adulthood. An adult-normed test compares a 55-year-old with other 55-year-olds, so normal aging does not masquerade as low intelligence.
Getting a clean number from your first sitting
Retesting inflates scores. A meta-analysis covering 107 samples and 134,436 participants found an adjusted average gain of about a quarter of a standard deviation on retakes, with larger gains when coaching was involved or the identical form was reused. Treat your first sitting as the cleanest estimate, and space any retake out; Mensa itself allows retesting only once every eight weeks.
Once you have a score, interpretation is its own subject. Our guide to the normal IQ score for adults explains what the average range looks like and how to read a score in context, so we will not repeat that here.
If you want an adult-normed score without a clinic appointment, the RIOT IQ test at riotiq.com was built for exactly that purpose: an adults-only norm sample, a published margin of error for every version, and results in minutes rather than weeks.
Frequently asked questions
What is the best IQ test for adults?
In clinical settings the WAIS-5 is the standard. For credible online testing, the RIOT IQ test is normed exclusively on adults 18 and older and publishes the margin of error for each version.
Can I take the WAIS online by myself?
No. Pearson restricts the WAIS-5 to qualified clinicians, so it is administered in person by a professional rather than sold to the public.
At what age do adult IQ tests start?
The WAIS-5 begins at age 16, Mensa offers testing from age 14, and the RIOT IQ test is for adults 18 and older.
How long does an adult IQ test take?
The WAIS-5 takes about 45 to 60 minutes with a clinician. Online, the RIOT IQ test runs about 13 minutes in its Basic version and about 52 minutes in its Full version. Mensa's session lasts one to two hours.
Does IQ change with age?
Your rank among age peers is fairly stable, with a correlation of .54 between ages 11 and 90 on the same test. Specific abilities do change, and processing speed declines, which is why adult tests use age-based norms.
References
1. American Mensa. (n.d.). Testing options and admission. us.mensa.org
2. Deary, I. J., Pattie, A., & Starr, J. M. (2013). The stability of intelligence from age 11 to age 90 years: The Lothian Birth Cohort of 1921. Psychological Science, 24(12), 2361-2368. doi.org/10.1177/0956797613486487
3. Hartshorne, J. K., & Germine, L. T. (2015). When does cognitive functioning peak? The asynchronous rise and fall of different cognitive abilities across the life span. Psychological Science, 26(4). doi.org/10.1177/0956797614567339
4. Hausknecht, J. P., Halpert, J. A., Di Paolo, N. T., & Moriarty Gerrard, M. O. (2007). Retesting in selection: A meta-analysis of coaching and practice effects for tests of cognitive ability. Journal of Applied Psychology, 92(2), 373-385. doi.org/10.1037/0021-9010.92.2.373
8. Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103(3), 403-428. doi.org/10.1037/0033-295X.103.3.403
